Catheters are used to insert cutting elements in body vessels, orifices, or conduits, such as arteries narrowed by atherosclerotic plaque and/or fibromuscular disease or to perform surgery within a constricted or obstructed ureter or urethra. Often, such catheters are of a dilation nature and serve to dilate the body vessels, orifices, and conduits. They basically consist of an elongated catheter, having an inflatable balloon or bladder at or near its distal end. A guide wire or other axial support means is often included to improve the torque control or "steerability" of the apparatus.
When a cutter assembly is inserted in the body vessel, orifice, or conduit, the cutting element carried by the cutting assembly must be properly aligned so that the cut made into the tissue or plaque is properly oriented. This is particularly important when the cutting element is carried by a dilation catheter and when the tissue is stressed and thereby subjected to significant trauma as it is cut by the cutting element. It would be highly undesirable if a cut was propagated in an undesirable direction since this might cause significant nerve and/or muscle damage. Fluoroscopy can be used to observe the cutter assembly as it is inserted into the patient. However, in many instances, for example, in prostate surgery, the fluoroscopic picture is a picture which looks downwardly upon the cutter assembly and the generally radiopaque cutting element, but does not readily show the precise orientation of the cutting element. Basically the cutting element shows up as a thin line under fluoroscopy and the precise orientation of the thin line is not readily apparent.
Radiopaque markings have been used to indicate the longitudinal positioning of balloons in body conduits. However, they have not been used to indicate angular orientation of such balloons (since balloons are generally radially symmetrical) nor have such markings been used to angularly orient cutters or the like in body conduits.
While the present invention is primarily contemplated as being useful with cutting elements it should be realized that it is more broadly useful with any device which is insertable in the body and which does not operate symmetrically but is instead sensitive to angular alignment about its longitudinal axis.
The present invention is directed to overcoming one or more of the problems as set forth above.